An Early Cretaceous lithostratigraphic and biostratigraphic framework for the Britannia Field reservoir (Late Barremian-Late Aptian), UK North Sea

A Lower Barremian-Upper Aptian lithostratigraphic scheme applicable to the Britannia Field (Blocks 15/29, 15/30, 16/26 and 36/27) is presented. The Br itannia Sandstone Formation reservoir is formally subdivided into three mem bers (type well 15/30-9); the Lapworth (Late Barremian to Early Aptian), Ki lda (Late Aptian) and Bosun (latest Aptian) members. The Lapworth Member is subdivided into three units, Lapworth 'A' (Late Barremian), the intra-Fisc hschiefer Lapworth 'B' (intra-Early Aptian) and Lapworth 'C' (Early Aptian) . The Early Barremian to Early Aptian upper Valhall Formation is subdivided i nto seven units:'V3A' the Hauptblatterton, 'V3B','V3C','V3D', Fischschiefer Bed, and 'V4'. The overlying Sola and Rodby Formations are subdivided into Units 'S1' and 'S2' of the 'Lower' Sola Formation (Late Aptian), plus Unit s 'S3' and 'S4' of the 'Upper' Sola Formation (Early Albian). The Rodby For mation (Middle? to Late Albian) is subdivided into three units: 'R2', 'R3' and 'R4'. A high resolution biostratigraphic zonal scheme is defined for the Early Ba rremian to earliest Albian interval, utilizing calcareous nannoplankton, mi cropalaeontology and palynology. Within this, 49 zones and 38 subzones (22 microfaunal zones and 4 subzones, 23 palynological zones and 19 subzones, a nd 14 nannoplankton zones and 15 subzones) are recognized. Of these, 5 micr opalaeontological zones (and 4 subzones), 11 palynological zones (and 15 su bzones) and 7 calcareous nannoplank ton zones (and 10 subzones) are directl y applicable to the Britannia reservoir section.